The Radio Songs chart (previously named Hot 100 Airplay)[1] is released weekly by Billboard magazine and measures the airplay of songs being played on radio stations throughout the United States across all musical genres. It is one of the three components, along with sales (both physical and the digital) and streaming activity, that determine the chart positions of songs on the Billboard Hot 100.

The airplay-only chart debuted as a 30-position chart on October 20, 1984. It was expanded to 40 positions on May 31, 1986, and to 75 positions on December 8, 1990.[2]

Each week, the Radio Songs chart ranks the 100 songs with the most airplay points (frequently referred to as audience impressions, which is a calculation of the number of times a song is played and the audience size of the station playing the tune). A song can pick up an airplay point every time it is selected to be played on specific radio stations that Billboard monitors. Radio stations across the board are used, from Top 40 Mainstream (which plays a wide variety of music that is generally the most popular songs of the time) to more genre-specific radio stations such as urban radio and country music. Paid plays of a song or treatment as bumper music do not count as an impression.

During the early years of the chart, only airplay data from top 40 radio stations (mainstream, adult pop and rhythmic), adult contemporary and modern rock formats were compiled to generate the chart. However, beginning in December 1998, the chart profile expanded to include airplay data from radio stations of other formats such as R&B, rock and country. To preserve the notion of the former chart, the Top 40 Tracks chart (now defunct) was introduced at the same time.

Singles usually enter the Radio Songs chart before any other, because in most cases, they hit the airwaves before being made commercially available online or in stores. Prior to December 5, 1998, the Hot 100 was solely compiled of songs that were commercially available. This means that songs could enter the airplay chart, but would not be eligible for the Hot 100 unless a commercial single in stores was issued. In the 1990s, numerous tracks such as "Don't Speak" by No Doubt, "Lovefool" by The Cardigans, "3 A.M." by Matchbox 20, "When I Come Around" by Green Day all did well on the Airplay chart, but were not allowed to enter the Hot 100 because no commercial single was available, even though they would have probably been significant hits on the Hot 100 without the need of a commercial single.

Due to circumstances like this becoming a growing trend with major record labels to release singles only to radio (as they felt commercial releases were a factor in decreasing album sales), many in the music industry requested that Billboard rethink its long-standing rule of "singles only" on the Hot 100. Billboard conducted extensive research and polls of music and recording industry insiders to assess the need for such a revamp of the chart, and it was concluded that allowing airplay-only singles into the Hot 100 was the correct choice, as the chart has always been a reflection of what songs are most popular in the United States. This new rule would present an accurate tool for those in the music industry to gauge the popularity of their "product" and to analyze marketing strategies, etc.

After December 5, 1998, songs could chart on the Hot 100 with just airplay points. However, before they were allowed onto the Hot 100, they had to make the Top 75 on the Hot 100 Airplay chart. Starting from the chart issue of February 12, 2005, songs without a retail component were allowed to chart on the Hot 100 regardless of their rank on the Hot 100 Airplay chart.[4] Songs that charted on the Hot 100 without a commercial single release were known as album cuts. The first airplay-only single to hit number one on the Hot 100 came in June 2000 when Aaliyah's "Try Again" spent one week at the top. The method of radio-only cuts eventually stopped after the incorporation of digital downloaded music-based points into the Hot 100, which made album cuts always available to download, even if not released as a single.